Electrically adjustable furniture piece comprising a drive motor

ABSTRACT

In a furniture piece including a furniture support part and an adjustable furniture part which is movable relative to the furniture support part by an electric drive motor, the electric drive motor is operable by a power supply at the power supply net voltage without galvanic separation between the power supply and the electric drive motor. The furniture pieces also include sensors for sensing motions of the furniture parts which motions are analyzed and compared with reference patterns to determine an occupation state of the furniture pieces.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part application of pending international patent application PCT/DE2018/100871 filed Oct. 25, 2018 and claiming the priority of German patent application 10 2017 125 390.4 filed Oct. 30, 2017. The said international patent application PCT/DE2018/100871 and the said German patent application 10 2017 125 390.4 are both incorporated herein by reference in their entireties as though fully set forth.

BACKGROUND OF THE INVENTION

The present invention resides in an electrically adjustable furniture piece including at least one electric drive motor for adjusting at least one adjustable furniture part relative to a furniture support part. The invention furthermore concerns a method for detecting the occupation state of a furniture piece.

Furniture pieces such as for example office tables with height-adjustable table plates supported by support legs are known. Integrated into the table legs are electric motors for the powered height adjustment of the table plate. Such a furniture piece is described for example in WO 2010/112574 A2.

DE 20 2016 104 512 U1 discloses an electrically adjustable furniture piece with a drive unit for adjusting an adjustable furniture part with respect to a furniture support part. The furniture piece, includes a sensor arrangement for detecting the inclination or an inclination change of the adjustable furniture part wherein the drive unit is controlled dependent on the inclination or, respectively, the inclination change. This makes it possible for example in a particular embodiment of the furniture piece in the form of a height-adjustable table to adjust the height by pressing the table edge upwardly or downwardly.

It is the object of the present invention to provide furniture pieces with movable parts operated by electric motors with simplified operating arrangements. It is furthermore an object to determine from motions of the furniture parts whether the furniture pieces are occupied.

SUMMARY OF THE INVENTION

In a furniture piece including a furniture support part and an adjustable furniture part which is movable relative to the furniture support part by an electric drive motor, the electric drive motor is operable by a power supply at the power supply net voltage without galvanic separation between the power supply and the electric drive motor. The furniture pieces also include sensors for sensing motions of the furniture parts which motions are analyzed and compared with reference patterns to determine an occupation state of the furniture pieces.

In one respect, the invention concerns an electrically adjustable furniture piece which includes one or several electric drive motors for adjusting at least one adjustable furniture part with respect to the furniture support part of the furniture piece. In accordance with the invention the adjustable furniture part can be adjusted with respect to the furniture support part at an increased speed.

The furniture piece may include a sensor arrangement by which the relative or the absolute position or a relative or absolute movement of the furniture part, for example, the relative position or a relative movement of the adjustable furniture part with respect to the furniture support part, can be detected, and wherein at least one of the electric drive motors is controlled depending on the detected position or movement of the adjustable furniture part.

At least one drive motor provided but preferably all the electric drive motors provided in the electrically adjustable furniture piece are motors which can be operated directly by a current with the voltage of the electric power supply net. Consequently, these are not drive motors which include the electrical isolation required for a direct connection to the public power supply net. Rather the power supply voltage of, for example, 230 V is applied directly without a galvanic separation between the public power supply net and the drive motors, that is, without a transformer which would provide for a separation from the public power supply net. Possibly, the drive motor may be energized by an electronic power supply unit providing a voltage which is lower than the power supply voltage.

A galvanic separation is to be understood to provide a separation between the public electric power supply and the drive motor. The omission of a galvanic separation means in connection with the present application, that the drive motor or the electronic power supply unit of the drive motor is conductively connected to the public power supply net.

Since in this way the power is no longer limited by a power converter, the electric drive motors can be energized for a significantly increased power output so that they can provide for example larger movements and higher movement speeds of the movable furniture part with respect to the furniture support part. It is also possible to adjust heavier movable furniture parts within a shorter-time then this would be possible with low-voltage drive motors which use a net power conversion unit for a galvanic separation and whose power supply is limited by the power generated by the power conversion unit.

Another advantage of the drive motors resides in the fact that, different from low voltage drive motors with galvanic separation, only relatively small power supply units are required for the control of the drive motors so that standby losses are reduced or do not occur at all. Also the controllers for the drive motors are significantly smaller since in the drive motors without galvanic separation only the initial stages are required for the control of the drive motors. Also the cooling requirements are significantly smaller than those for low-voltage drive motors since, because of its different and smaller design, the power supply unit generates less heat. With lower losses also greater efficiency is reached.

With its relatively small size—among others also the controller—may be arranged in a space-saving manner for example in a motor box at the top of a table leg or at a location where usually the operating parts are arranged. Furthermore, it is advantageous that the number of drive motors that can be connected to a controller can be relatively large since there is no limit for the number of drives connected to a power supply. Because of the lower heat generation longer operating periods for the drive motors, also at higher loads can be realized or, respectively, shut-off phases are no longer required.

Advantageously the furniture piece includes at least two electric drive motors for adjusting the adjustable furniture part. In an advantageous embodiment those are controllable independently from one another. All electric drive motors are operable by the public power supply. It may also be expedient to provide a common controller for at least two electric drive motors.

If several drive motors are used it may be necessary to synchronize the drive motors during the adjustment process so that a certain surface area of the furniture piece, for example a table top, remains level during adjustment. By evaluation of sensor signals of a sensor arrangement, the drive motors can be so controlled that they run synchronously so that the exemplary table top remains level.

The sensor arrangements may include for example a gyro-sensor and a gravity sensor. The signals of the gyro-sensor and of the gravity sensor which supplies an absolute inclination value, are combined herein. The height of the adjustable furniture part can be determined by an additional distance sensor which measures the distance from the floor, from a reference value or the ceiling.

The independent control of the electric drive motors permits a simple set-up, in particular in that the different electric drive motors are controlled by different sensor signals. Also with this simplified arrangement a desired inclination position of the adjustable furniture part with respect to the furniture support part can be maintained. One of the electric drive motors executes automatically and independently of the other drive motor a compensation movement. Via the sensor arrangement an inclination or inclination change of the adjustable furniture part is determined already during the adjustment movement of the adjustable furniture part and compensated for by a corresponding control of the respective electric drive motor.

For the adjustment of an adjustable furniture part, for example a table plate, the furniture piece may be provided with two electric drive motors of which a first electric drive motor may be so controlled that a desired speed is maintained. The second drive motor is via sensor signals so controlled that a desired inclination of the adjustable furniture part is maintained. The sensor signals indicate the actual state of the movable furniture part concerning its position and/or speed level.

The sensor signals for the first drive motor are generated for example by Hall sensors via which the momentary height as well as the speed is being determined. The drive motor is then controlled in such a way that it maintains a desired speed. The second drive motor does not have a Hall sensor but is controlled via signals of gyro/gravitation sensors which are associated with the first drive motor or the controller, in such a way that the adjustable furniture part maintains a desired inclination, for example, so that a table top remains horizontal. If the gyro/gravitation sensor is present anyway for collision sensing for the second drive motor and, if present, additional drive motors no Hall sensors including cables, plugs, and evaluation electronics are needed.

An embodiment including a so-called master leg provided with a drive motor to be controlled by an operator is also possible. The other legs are provided with drive motors which include individual controllers and gyro/gravity sensors and which control the motors to provide for a desired inclination of the adjustable furniture part so that for example the table top remains horizontal as these drive motors are actuated so as to provide for the desired inclination.

Also other embodiments may be considered wherein each electric drive motor has its own controller as well as embodiments with a common controller for at least two drive motors. In the embodiments with separate controllers as well as in the embodiments with a common controller an independent control of the various electric drive motors may be provided.

In a further advantageous embodiment there is one drive motor whose adjustment movement is transmitted to different adjustable furniture parts via a transmission arrangement. There may be for example a single drive motor for the height adjustment of a table wherein the movement of this drive motor is transmitted to two table legs via the transmission arrangement.

In a further advantageous embodiment the at least one electric drive motor can be switched on and off by a control unit which is integrated into the housing of the controller which controls the electric drive motor. The control unit may for example be inserted into the housing of the controller in the form of a pre-assembled device wherein advantageously with the insertion the device mechanical contacts are established with switches on a circuit board of the controller. The control unit includes operating elements such as buttons which can be actuated manually by a user for switching the switches on the circuit board of the controller on and off. The operating elements are provided with extensions which are long enough to provide for a sufficient distance of for example 6 mm from a circuit board of the controller which is energized by a power supply voltage.

Alternatively, the housing of the controller and/or the control unit may consist of a material that permits a direct contact with electrically charged components. In this case, a small distance between the operating elements of the control unit and the circuit board of the controller which is subjected to the power supply voltage may be sufficient.

It may be expedient to provide a housing of the controller which preferably consists of a plastic material with a relatively thick wall to increase the stability thereof, for example with a wall thickness of at least 2 mm. The increased stability of the housing ensures that the housing is not destroyed by forces to which it is normally subjected. For example, in case of a height adjustable table the controller housing should be able to withstand a load as it may occur when during lowering a table the table plate accidentally hits an object such as for example a chair back rest or a similar object.

Rather than having operating elements which mechanically activate switches on the circuit board of the controller, the operating unit may be provided for example with capacitive actuating areas, which are actuated by the user. The change of the capacitance upon touching the actuating areas serves as a signal for switching the electric drive motors on or, respectively, off.

In still a further advantageous embodiment, the operating unit for switching the drive motor on or off includes a light source and a phototransistor, that is the operating unit cooperates with a light source and a phototransistor. As light source, for example on LED or an IR-LED is used. The light source may be directed toward an operating panel of the operating unit so that the light emitted by the light source is reflected from for example a finger on the operating panel, which is sensed by the phototransistor.

In this embodiment the operating unit is preferably transparent or at least semi-transparent so as to make the light emitted by the light source visible. This has the advantage that the controller is hermetically enclosed in the housing.

The LED and the photo transistor are supported for example on the control board.

It is also possible to conduct the light of the light source to the operating unit via a light conductor. By way of the light conductor, light can be supplied to the operating unit over a large distance so that the operating unit can be arranged at a greater distance from the controller.

In accordance with a still further advantageous embodiment the operating unit is provided with an indicator on which a momentary characteristic value of the adjustable furniture part is shown, for example the momentary height of a table.

In another advantageous embodiment, the operating unit for the on and off switching of the drive motor comprises a wireless transmission unit for transmitting a signal to the controller or it cooperates with another radio transmitter, The radio transmitter uses for example Bluetooth, BLE or WiFi. This embodiment has the advantage that no electrical cable which, for safety reasons, would have to be electrically isolated, is needed. Activation may be achieved for example by remote operation or via a smart phone.

In a further advantageous embodiment the controller includes a communication port for configuration wherein a configuration is executed via an external apparatus which can be connected to the controller, for example via a connected personal computer. Into the communication port an interface element may be inserted which contains the galvanic separation.

In a still further advantageous embodiment the controller is controlled via a PWM signal in each case with a Low-Side Mos Fet for each direction of rotation, while the high-side is controlled in each direction of rotation with a thyristor and the thyristor again is controlled via an Optotriac or Opto thyristor. In this way, a full bridge for the control of the electric drive motor can be provided at relatively low expenses.

For recognizing the momentary characteristic value of the adjustable furniture part, for example for reorganizing the momentary table height, it may be advantageous to provide the drive motor with a signal generator for the recognition of the momentary speed. To this end for example Hall sensors may be used which sense a magnetic field which is generated by a magnet arranged on the motor—or drive shaft. With the use of two Hall sensors it is also possible to determine the direction of rotation of the motor.

In an alternative embodiment only a single sensor may be used, for example a Hall sensor or a light barrier. The Hall sensor cooperates with a magnet which is advantageously so magnetized that a pole change with a small distance is followed by another pole change again with a small distance and a subsequent pole change with a long distance. This makes it possible to determine the direction of rotation. In case a light barrier is used, a disc arranged on the motor or drive shaft is assigned to the light barrier which disc has openings of different length which are provided on the disc in a circumferential direction one after the other, an annularly longer opening and two shorter openings. Also, in this way it is possible to determine the direction of rotation with a single light barrier.

In accordance with a further advantageous embodiment of the invention the drive motor is provided with a counter which counts the number of rotations of the motor wherefrom the momentary position and, consequently the characteristic value of the adjustable furniture part such as for example the table height can be determined. The counter must be adjusted by a reference value for the determination of the momentary characteristic value. The adjustment with the reference value may be made already during installation.

In a further advantageous embodiment an interface is arranged between the controller and the drive motor, whereby, communication between the controller and the drive motor is established. In this way impulses resulting from the drive motor can be evaluated whereby with the recognition of the impulses including the length of the impulses, the direction of rotation and the absolute characteristic value, for example the absolute height can be determined.

In a method for operating one or several furniture parts, which, as described above, are each provided with several electric drive motors operated by the power supply voltage, at least two electric drive motors in the same or different furniture pieces may be synchronized via the power supply. This permits a synchronization also over large distances without communication cables.

As drive motors, which are operated directly by a power supply without galvanic separation, for example universal motors, permanently magnetized collector motors or brushless DC motors may be used.

In a further aspect the invention concerns a method for determining the occupation state of at least one furniture piece. The furniture piece is provided with a sensor arrangement for determining a movement of an adjustable part of the furniture piece.

The occupation state of the furniture piece refers to the question whether the furniture piece is occupied by a person. The occupation state means for a furniture piece in the form of a table, such as a height-adjustable table, whether a person is sitting or standing at the table and in this way, occupies the table. If the furniture piece is a seat, for example a chair, a movable furniture part is formed for example be a seat top which is height adjustable with respect to a seat base structure which forms a furniture support part. The occupation state determines whether or not the chair is occupied by a person.

With the method a movement of the movable furniture part is detected by a sensor arrangement which is preferably integrated into the furniture piece. The detected movement may be an absolute movement of the furniture part in a room for example the tilting movement of a table wherein via the sensor arrangement for example an inclination change of the table plate is detected.

Additionally or alternatively, a relative movement may be determined by the sensor arrangement. In this case the furniture part, the movement of which is detected, forms an adjustable furniture part which is movable with respect to a furniture support part.

The movement is detected for a limited or unlimited period, whereby a movement pattern of the furniture part can be determined. This movement pattern of the movable furniture part is compared with a reference movement pattern. If the detected movement pattern of the movable furniture part corresponds with the reference movement pattern it is assumed that the furniture part is in an occupied state, that is, the furniture part is occupied by a person. In this case, a corresponding occupied signal is generated.

Consequently, with this process the movement state of a furniture piece which is associated with a sensor arrangement can automatically be recognized. The furniture piece may include at least one adjustable furniture part and a furniture support part wherein the relative movement of the adjustable furniture part relative to the furniture support part is recognized.

Subsequently, the occupation signal can be further processed centrally or decentrally and utilized for example for the control of one or several technical arrangements which are present in the furniture piece or around the furniture piece. It is for example possible, with the furniture piece determined to be occupied, to control one or several light sources in the furniture piece or outside the furniture piece, or to set the room temperature to a certain value, or similar. It is further possible to refer a person looking for a seat or a working place to an unoccupied furniture piece.

In a preferred embodiment the sensor arrangement is provided in the furniture piece. The sensor arrangement may be arranged in the adjustable furniture part or in the furniture support part or in both furniture parts. It is also possible to detect either directly a relative movement between the adjustable furniture part and the furniture support part or a movement of the adjustable furniture part relative to the floor or another nearby object wherein the furniture support part is firmly supported on the floor so that a movement of the movable furniture part represents a movement relative to the furniture support part.

There may be various possibilities for relative movements of the adjustable furniture part relative to the furniture support part. In accordance with an advantageous embodiment the inclination of the adjustable furniture part relative to the furniture support part may be changed, for example the inclination of a table plate which is part of an adjustable furniture part with respect to a support base of the table, that is for example one or several table legs. By observing the inclination over a certain period an inclination change of the adjustable furniture part can be determined and compared with a reference movement pattern.

Advantageously, the movement of the adjustable furniture part—absolute or relative to the furniture support part—can be constantly surveilled and compared with the reference pattern as soon as a movement of the adjustable furniture part has been detected by the sensor arrangement during a minimum period.

Generally, this procedure has the advantage that sensor arrangements already existing in the furniture piece or outside the furniture piece can be used for detecting the occupation state of the furniture piece. All sensor arrangements, with which a relative movement of the adjustable furniture part with respect to the furniture support part or with which an absolute movement of a furniture part can be detected, are suitable. By recording the movement over a certain period a movement pattern of the adjustable furniture part is obtained which can be compared with the reference movement pattern.

By establishing a reference movement pattern collection for the comparison with the sensed movement pattern it becomes possible to distinguish between a movement indicating the occupation state and another movement of the adjustable furniture part. When an adjustable furniture part is being occupied by a person, a characteristic movement pattern is generated which can be detected by the sensor arrangement and subsequently compared with the reference movement pattern. The characteristic movement pattern of a furniture piece that is occupied differs from other movements of the furniture part which are generated intentionally by the person occupying the furniture part. It is therefore possible to adjust with the same sensor arrangement a defined position of the adjustable furniture part automatically or manually, to recognize a collision with another object and also the movement state of the furniture piece.

In accordance with another expedient embodiment the furniture piece is provided with at least one electric drive motor for adjusting the adjustable furniture part with respect to the furniture support part. The movement pattern of the adjustable furniture part, by which the occupation state is detected, is preferably sensed during a rest phase of the electric drive motor. In an alternative embodiment the movement pattern of the adjustable furniture part for determining the occupation state can be determined during an adjustment movement of the electric drive motor. In the latter case, the movement pattern characteristic for occupation state superimposes the adjustment movement of the adjustable furniture piece which is caused by operation of one or several electric drive motors.

In accordance with a further expedient embodiment, the occupation state of several furniture pieces is detected which are similar and comprise for example exclusively tables or exclusively chairs. The occupation signals of one or several furniture pieces are advantageously supplied to a central location, where they are further processed for example by a control of one or several technical devices depending on the occupation signals. A furniture piece which is not occupied may be assigned to person. It is consequently possible to determine in the central location, the occupation state of the furniture pieces, and assign non-occupied furniture pieces each to a person. This procedure permits for example in companies not to assign a certain working place to a certain person but introduce a variable working place assignment which results in a higher occupation rate of the furniture pieces.

The sensor arrangement may for example include a high-resolution gyroscope sensor via which a rotation or, respectively an angular change of the adjustable furniture part with respect to the furniture support part can be determined. Additionally or alternatively, the sensor arrangement may include a gravitation sensor via which the absolute inclination of the adjustable furniture part can be determined. The height of the adjustable furniture part can be determined via a distance sensor of the sensor arrangement, which senses the distance from the floor, from a reference or from the ceiling. The height of the adjustable furniture piece can alternatively be determined by a Hall sensor which is arranged in the drive motor. The sensor arrangement may include one or several motion sensors.

The sensor arrangement may be part of a control arrangement including a controller in which the control signals of the sensor arrangement are processed and control signals for the control of one or several drive motors are generated via which the adjustable furniture part is adjusted. The control arrangement may be integrated into a drive which comprises the drive motor and a transmission and, if present, connection and transfer components which may also be arranged outside of the drive. Furthermore, the sensor arrangement may be integrated into the controller, but it may also be arranged outside the controller. The controller may be attached to the adjustable furniture part or to the furniture support part.

If the occupation state of several furniture pieces is determined, the occupation signals are preferable supplied to a central location. The transmission of the occupation signals of each furniture piece to the central location occurs either via transmission cables or by wireless transmission. In the central location the signals are advantageously evaluated and persons are assigned to non-occupied furniture pieces. From there, also one or several technical devices which are either disposed in the furniture pieces or on the outside are controlled.

The invention and further advantages and expedient embodiments thereof will be described below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

It is shown in:

FIG. 1, in a side view, a section of an adjustable table with a table plate which is height-adjustable with respect to a table leg,

FIG. 2 the table section with the table plate raised,

FIG. 3 the complete table in a side view showing an electric drive motor in both, the left and right table legs,

FIG. 4 a schematic representation of several tables with a transmission of the occupation state of each table to a central unit,

FIG. 5 a perspective view of a controller for controlling an electric drive motor, and;

FIG. 6 a longitudinal sectional view of the controller.

DESCRIPTION OF A PARTICULAR EMBODIMENT

Identical components shown in the various figures are designated by the same reference numerals.

In FIGS. 1 and 2 as an exemplary furniture piece a table 1 is shown with a table plate 3 supported on a table leg 2. The table leg 2 forms the furniture support part and the table plate 3 forms the adjustable furniture part, wherein the table plate 3 is height adjustable with respect to the table leg 2. The table plate 3 is height-adjustable by an electric drive motor 4, which is arranged at the bottom side of the table plate 3 and mounted on a guide member 3 a which extends into the table leg 2 and is slidably guided therein. The drive motor 4 rotates a worm gear shaft 5 which extends into a counter thread in the table leg 2 so that a desired height adjustment of the table plate 3 is achieved by a rotation of the shaft 5.

At the bottom side of the table plate 3 there is a control arrangement 6 for controlling the electric drive motor 4. The control arrangement comprises a controller and a sensor arrangement 7 whose sensor signals are processed in the controller to provide control signals by which the drive motor 4 is controlled. The electric drive motor 4 can be controlled to rotate in either direction of rotation in order to either raise the table plate 3 or lower it.

The sensor arrangement 7 includes for example a gyroscope sensor for determining the inclination of the table plate 3 with respect to the table leg 2 or an absolute pivot movement of the table plate, and a gravitation sensor which provides an absolute inclination value. The height of the table plate 3 can be determined via a distance sensor which measures the distance from the floor, from a reference or from the ceiling. Also the distance sensor may be part of the sensor arrangement 7.

In FIG. 3 the whole table 1 is shown in a side view wherein two table legs 2 are visible which together support the table plate 3. Into each of the table legs 2 a guide member 3 a extends from the bottom side of the table plate 3 and each guide member 3 a carries an electric drive motor 4, via which the respective guide member 3 a can be height-adjusted with respect to the table leg 2. The two electric drive motors 4 are both controlled by the control arrangement 6 which includes a sensor arrangement 7 that operates without contact. The over-all control via the sensor arrangement 7 occurs via a manual gesture in a sensing area indicated by the arrow 8 above the sensor arrangement 7 and the upper side of the table plate 3.

The two electric drive motors 4 may be controlled via the common control arrangement 6 in a synchronous manner. But an independent control of the two electric drive motors 4 is also possible. This makes it possible to adjust the table plate 3 to a desired inclination for example to adjust the table plate 3 to a horizontal orientation in spite of an uneven floor or to a certain desk inclination. If several sensors are arranged in the sensor arrangement 7 correspondingly more degrees of freedom of movement of the table plate 3 can be determined and adjusted to the desired values by the various drive motors.

The electric drive motors 4, which are provided on the table 1 in the earlier described exemplary embodiments, are preferably motors which are operated by the public electric power supply without galvanic separation between the electric power supply and the drive motors. Such drive motors, which are connected to the normal power supply net, have the advantage that a transformer is not needed. However the motor may also be operated via a power electronic device with a lower power supply voltage. The control arrangements or, respectively, controllers can have smaller dimensions. Furthermore less waste heat is produced in spite of a higher performance so that the availability of the electric drive motors is increased.

The drive motors may be for example universal motors, permanent magnetized collector motors or brushless DC motors.

Various electric drive motors, in particular in different furniture pieces may, based on their design as power supply motors, be synchronized via the power supply net. This has the advantage that the drive motors can be synchronized also over larger distances without the need for communication cables.

FIG. 4 shows an exemplary embodiment including a plurality of furniture pieces 1, each in the form of a table with a height adjustable table plate. Via the sensor arrangement in each table, the momentary occupation state that is the occupation of a table by a person can be determined for each table. To this end, the sensor information of the sensor arrangement in each table 1 is evaluated by a comparison with a reference movement pattern. The data collection via the sensor arrangement in each table 1 occurs over a minimum period in order to obtain a sample movement of the adjustable furniture part in the form of the table plate, from which the momentary occupation state information is derived.

As soon as a person is sitting or standing at a table and applies a load to the table plate which is typical for office work, such as placing their arms onto the table plate and/or writing on the table plate a movement pattern is developed which is typical for the particular activity and which is sensed by the sensor arrangement provided on the table plate. The sensed movement pattern is compared with a reference movement pattern and if there is sufficient conformity between the sensed movement pattern and the reference movement pattern it is concluded that the table is occupied by a person. This reference movement pattern which is typical for an occupied table differs from a movement pattern that is for example generated during raising or lowering the table plate during an adjustment of the table plate inclination or an accidental jolt to the table plate. It is as a result possible to distinguish different movement patterns and, in particular, to identify the occupation state of the table. The identification can be performed during a resting period of the electric drive motors of the table 1 but also during a correction movement of the drive motors. In the latter case the movement pattern typical for the occupation state is obtained by a superimposition of different movements comprising the adjustment movement by the operation of the drive motors and additionally the movement pattern of the table plate caused by the person occupying the table.

For each table 1 an occupation signal 12 is generated from a comparison of the sensed movement pattern with the reference movement pattern. For each table which is not occupied, the occupation signal 12 may have the value 0 and for each occupied table the occupation signal may have the value 1.

The occupation signals 12 are all transmitted to a central location 9. They are transmitted either by wireless transmission or via data or, respectively, communication lines. The occupation signals 12 are evaluated in the central location 9 for example so as to determine a balance between actually non-occupied tables 1 and a need for non-occupied tables. This facilitates to assign tables to persons who are looking for an unoccupied table.

The central location 9 controls a display unit 10 on which the non-occupied tables 1 are optically indicated so that persons seeking a non-occupied table can easily find one. Additionally or alternatively, technical devices 11 may be provided, for example lighting devices, which are activated depending on the occupation state of the table to switch the lights on for occupied tables or heating or cooling devices for heating or cooling the surroundings of occupied tables.

FIG. 5 shows a controller 13 for an electrical drive motor with a housing 14 for accommodating a circuit board of the controller. The housing 14 of the controller 13 consists in particular of a plastic material which may be glass-fiber reinforced. As plastic material for example PA 66 or a polycarbonate may be used. The housing 14 may have a wall thickness of for example at least 2 mm, to provide for high stability. At the inside wall of the housing 14 there may be longitudinal grooves 17 (FIG. 6) into which the circuit board of the controller is inserted.

In the area of a front side of the housing 14 there is an operating unit 15 with operating buttons 16 for switching the electric drive motors on and off. The operating unit 15 covers the front side of the housing 14 so that the interior of the housing is hermetically closed. The operating unit 15 may also consist of a plastic material. With the integration of the operating unit 15 into the housing 14 of the controller, a compact space-saving arrangement is obtained. In an embodiment of the furniture piece in the form of a height-adjustable table, the controller 13 is arranged for example below the table adjacent the front edge thereof. Because of the high stability of the housing 14 it can be subjected to relatively high forces without the danger of being destroyed.

Since there is no galvanic separation between the power supply net and the drive motor or, respectively, the controller 13, the operating unit 15 with the operating buttons 16 is arranged in the interior of the housing 14 with a sufficient distance of for example 6 mm from the circuit board. The distance may be bridged for example by extensions of the buttons 16 via which the switches on the circuit board can be operated. Alternatively, the signals may be transmitted to the circuit board contact-free for example by the use of light sources and photo transistors disposed on the circuit board and respectively on the operating unit or by the use of a radio module for the signal transmission. 

What is claimed is:
 1. An electrically adjustable furniture piece including at least one electric drive motor (4) for adjusting at least one adjustable furniture part (3) relative to a furniture support part (2) of the furniture piece (1), wherein the drive motor (4) is an electric motor operable by a power supply voltage without galvanic separation between the power supply net and the drive motor (4).
 2. The furniture piece as claimed in claim 1, wherein an operating unit for switching the drive motor (4) on and off, for recalling stored positions and a height indication is integrated into the housing of a controller (13) for at least one electric drive motor (4)
 3. The furniture piece as claimed in claim 2, wherein the operating unit for switching the drive motor (4) on and off comprises a light source and a phototransistor or cooperates with a light source.
 4. The furniture piece as claimed in claim 2, wherein the operating unit for switching the drive motor (4) on and off is a radio module for a signal transmission to the controller (13).
 5. The furniture piece as claimed in claim 2, wherein the controller (13) is provided with a communication port for a configuration of the controller (13) via an external, connectable apparatus.
 6. The furniture piece as claimed in claim 1, wherein the drive motor (4) is one of an universal motor, a permanent magnet excited collector motor and a brushless DC motor.
 7. The furniture piece as claimed in claim 1, wherein at least two electric drive motors (4) are arranged in the furniture piece (1) for adjusting the adjustable furniture part (3) with respect to the furniture support part (2).
 8. The furniture piece as claimed in claim 7, wherein the least two electric drive motors (4) are controllable independently of one another.
 9. The furniture piece as claimed in claim 7, wherein a common controller (13) is provided for the at least two electric drive motors (4).
 10. The furniture piece as claimed in claim 7, wherein at least one of the at least two drive motors (4) is controllable exclusively dependent on sensor signals generated by Hall sensors whereas the other drive motor or motors are controllable exclusively by an evaluation of gyro/gravitation sensor signals.
 11. The furniture piece as claimed in claim 1, wherein the furniture piece is provided with a sensor arrangement (7) determining a position or movement of an adjustable furniture part (3) and at least one drive motor (4) is controllable depending on the position or movement determined by the sensor arrangement (7).
 12. A method for operating at least one of the furniture pieces (1) as claimed in claim 1, wherein at least two electric drive motors (4) arranged in one or in several furniture pieces (1) are synchronized via the power supply net.
 13. A method for determining an occupation state of a furniture piece (1) according to claim 1, with a sensor arrangement (7) for detecting a movement of an adjustable furniture part (3) of the furniture piece (1) wherein the furniture piece (1) is determined to be occupied by a person and an occupation signal (12) is generated if it is determined via the sensor arrangement (7) that a movement pattern of the adjustable furniture part (3) corresponds to a particular reference pattern normally generated when the furniture piece is occupied.
 14. The method according to claim 13, wherein via the sensor arrangement (7) an absolute movement of the movable furniture part is detected.
 15. The method according to claim 13, wherein the furniture part (3) the movement of which is sensed by the sensor arrangement (7) is an adjustable furniture part (3) which is adjustable with respect to a furniture support part (2) of the furniture piece (1) and wherein a relative movement of the adjustable furniture part (3) with respect to the furniture support part (2) is detected by the sensor arrangement (7).
 16. The method according to claim 15, wherein the furniture piece (1) includes at least one electric drive motor (4) for adjusting the adjustable furniture part (3) with respect to the furniture support part (2), and the movement pattern of the adjustable furniture part (3) for detecting the occupation state of the furniture piece (1) is detected during a resting phase of the electric drive motor (4).
 17. The method according to claim 15, wherein the furniture piece (1) includes at least one electric drive motor (4) for adjusting the adjustable furniture part (3) with respect to the furniture support part (2) and the movement pattern of the adjustable furniture part (3) for detecting the occupation state of the furniture piece is detected during an adjustment movement by the electric drive motor (4).
 18. The method according to claim 15, wherein the furniture piece (1) is in the form of a table with a height-adjustable table plate forming the adjustable furniture part (3) and at least one table leg forming the furniture support part (2), and wherein the movement pattern of the table plate (3) is detected with the aid of the sensor arrangement (7).
 19. The method according to claim 13, wherein an inclination change of the adjustable furniture part (3) is detected by the sensor arrangement.
 20. The method according to claim 13, wherein the occupation signal (12) of the furniture piece (1) is supplied to a central location (9).
 21. The method according to claim 13, wherein depending on the occupation state of the furniture piece (1) at least one technical device (11) associated with the furniture piece (1) or arranged nearby is controlled.
 22. The method according to claim 20, wherein the occupation state of several furniture pieces (1) is determined of which each is provided with a sensor arrangement (7) for determining an adjustment movement of the adjustable furniture part (3) and the occupation signals (12) of occupied furniture pieces (1) are supplied to the central location (9).
 23. The method according to claim 22, wherein in the central location (9) at least one of the non-occupied furniture pieces (1) is assigned to at least one person. 